not a natural rock

Concrete / Anthropogenic Conglomerate

Man-made composite material (Portland cement, aggregate, and water)

AI-generated identification · may be incorrect

Hardness: 3–7 Mohs (variable depending on aggregate); Color: Grey, off-white, or tan; Luster: Dull/Earthy; Structure: Amorphous paste binding crystalline rock fragments; Specific Gravity: Approx. 2.4

Hardness: 3–7 Mohs (variable depending on aggregate)
Color: Grey, off-white, or tan
Luster: Dull/Earthy

Identified March 23, 2026More not a natural rock →

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Physical properties

Formation & geological history

Formed through a chemical hydration process where water reacts with Portland cement to bind aggregates (sand/gravel). This specific specimen appears to be demolition debris or 'technofossil' from human construction.

Uses & applications

Primary building material for infrastructure, housing, and roads; as debris, it is often recycled as road base or fill.

Geological facts

Concrete is the most widely used man-made material on Earth. In geological terms, it is considered an 'Anthropogenic' or 'Technogenic' rock because it mimics the natural conglomerate formation process.

Field identification & locations

Identify by its grey, gritty matrix and the presence of mixed, often angular, rock fragments. It is commonly found near construction sites, urban areas, and demolition landfills.